Note that the word 'Doom' is used in the title of the Ring of Doom in the sense of 'judgement'; this was the place where the Valar reached the momentous decisions that would affect all of Arda, often rendered by Mandos in his role as the Doomsman of the Valar.

Notes

1

The text of The Silmarillion is a little ambiguous on the location of the Ring of Doom, saying only that it was 'near to the golden gates of Valmar'. On that basis, it could be imagined inside the city itself (and indeed we might expect that to have been the more reasonable location). However, there are various references that imply that it was outside the city near the base of the Two Trees, and in his index to The Silmarillion Christopher Tolkien describes it explicitly as 'outside the gates of Valmar'.